About 800 years ago, Native Americans in the Southwest began building stone citadels and sky-high pueblos. What were they afraid of?

The attackers probably struck the sleeping pueblo at dawn. Dozens of warriors, moving as silently as the rising sun in the cold desert air, climbed to the flat roofs of the tightly clustered multistory dwellings. The pueblo's 150-odd rooms had neither windows nor ground-level doors; a ladder propped against a small hole in the roof was the only way in or out of each dwelling. The invading warriors quickly pulled out the ladders, trapping the occupants inside. They lit shredded juniper bark and highly flammable greasewood and threw the flaming bundles into the rooms. The warriors fed the growing fire with more and more wood; some snatched bunches of chilies that were drying on the pueblo walls and tossed these into the inferno, creating smoke that would have stung like tear gas. Soon the flames reached the roof beams, and the attackers had to jump from the roofs before they collapsed. All around the pueblo, roofs were caving in, silencing the screams within.

On a late summer afternoon seven centuries after that massacre, Salmon Ruin, as the ancient, long-abandoned pueblo is now known, is serene, its stillness broken only by the cackle of scrub jays. Named after an early homesteader, Salmon Ruin lies a few miles east of Farmington in northwestern New Mexico. Exactly how the conflagration there unfolded can never be known, but Harvard archaeologist Steven LeBlanc believes the scenario he pieced together based on oral legends of similar battles of the Hopi, who live about 150 miles to the west, is plausible. He points to some blackened stone on a ruined wall. "You can see where it burned. And pueblo rooms don't burn easily," he says.

Here, on the quiet outskirts of a small town, it's difficult to imagine the carnage. In 1973 archaeologists digging at the site uncovered the bones of 33 children who were apparently burned alive inside a kiva, a large circular structure used for religious ceremonies. The children must have been hiding there during the attack, which occurred sometime between 1263 and 1300, according to tree-ring dating of wood at the scene. Archaeologists studying the children's skeletal remains noted signs of what they call green-bone burning—bone that has burned with flesh still attached.

Casual visitors to the site will learn none of this. Inside the small museum at Salmon Ruin, no mention is made of the slaughter. The omission does not surprise LeBlanc, the director of collections at Harvard's Peabody Museum of Archaeology and Ethnology. After three decades spent studying similar sites in New Mexico, Colorado, Utah, Arizona, and northern Mexico, he is convinced that most archaeologists have completely misread the region's archaeological record. Many of his colleagues even deny that a bloody battle was fought here. Instead, they attribute the deaths to accidental burning or ritual sacrifice.

Archaeologists have long believed that the pueblo-dwelling corn farmers who populated the southwest before Europeans arrived in the 16th century were a peaceful people. On the contrary, LeBlanc argues, prehistoric warfare in the Southwest was common, prolonged, and at least as deadly on a per capita basis as the most violent conflicts of the 20th century. Much of what we take to be characteristic of pueblos today—the magnificent, haunting cliff dwellings, the sophisticated architecture—is testimony to intense warfare and the deaths of entire tribes.
Clear evidence of prehistoric conflict can be difficult to discern in other parts of the world, but the arid climate and sparse settlement in the Southwest have left pueblo ruins, cultural artifacts, and even human remains remarkably intact. "My real interest is, How did people live in the past on a worldwide basis?" says LeBlanc. "What the Southwest provides us is probably the best-worked-out archaeological database in the world. We use it as an example, a place to test ideas. But ultimately it's not unique; it's not even particularly bloody. It's no different from anyplace else in the world.

"When I first began studying this, I asked, Was there any warfare among prehistoric cultures? Now, of course, my conclusion is that that's a completely stupid question. The real question that any archaeologist has to face is, Was there any peace?"

In 1972, when LeBlanc was a 29-year-old assistant professor at Wichita State University, he received a grant from the National Science Foundation to study a series of ruins in El Morro Valley in western central New Mexico. The valley is beautiful, an expanse of sweeping plains and mesas clothed in ponderosa pine. But at 7,200 feet above sea level, the cold nights and scant rainfall make it unsuitable for agriculture. Yet during the late 13th century, the valley had one of the largest pueblo populations in New Mexico. Some pueblos had more than 1,000 rooms; many had hundreds.

At a small hotel in Dolores, Colorado, where LeBlanc is preparing for a lecture at a nearby museum, he talks about that early work at El Morro: "What were these people doing at 7,200 feet in such a crummy place, trying to be corn farmers? That was our question. We wrote an application to the National Science Foundation and never mentioned the word warfare once."

What they found at the site raised other interesting questions.

"About the second day we were at El Morro, we walked over the site and could see evidence of burning—everywhere. So we began to excavate. We found rooms like this," he says, pointing to a slide showing the freshly excavated interior of a room at the pueblo. Broken pottery litters the floor, probably smashed when roof beams collapsed in a fire.

"The people obviously ran out the door in a hurry," says LeBlanc. "Everything was sitting on the floor just like they left it. Virtually every room in this site, which consisted of 20 distinct little pueblos, ranging from 5 to 10 rooms to maybe 30 rooms, spread out over a long ridge, had been catastrophically burned."

Natural fires in a stone pueblo quickly burn out or the community extinguishes them, usually before more than one room is damaged. The torching of an entire pueblo, LeBlanc's team concluded, must have been an act of war.
LeBlanc and his crew also noticed that many walls they excavated were missing large numbers of stones. This puzzled them until they uncovered a much bigger pueblo, consisting of 500 rooms and enclosing a central plaza, just a few hundred feet away. The second site was completed no later than 1279. According to tree-ring dates, the neighboring smaller pueblos were burned in 1276.

"What I believe happened was that the survivors dismantled those small scattered pueblos, which were not defensible, and they basically built a fortress," LeBlanc says. "These people were very afraid of something." At first, he recalls, "I explained it in terms of a very local, accidental kind of thing, like the Hatfields and the McCoys, that didn't have any broad explanation."

Only in the last several years has LeBlanc come to believe that El Morro represents just one episode from an era of violence that swept the Southwest, and probably much of North America, at the close of the 13th century. The evidence for widespread catastrophe is overwhelming, he says, from palisaded Iroquois villages in New York to fortified sites in the Pacific Northwest.

"It took me 25 years to come to grips with what was really going on," he says.